There are no big miracles or small miracles. A miracle involves the intervention of God. Also, there are no big sins or small sins, Sins are all equal.
We could stand to be be careful here. Some sins create greater troubles than other sins, and corrupt more things than other sins, so in that aspect, yes there are big and small sins — and yet all have a common element: they are the result of a relationship with the demonic world that God permitted us to throw ourselves into and yet He hates. God is concerned about individual sins, but even more fundamentally so about our relationship to Him. The sin that is the worst is the one which wilfully and dedicatedly closes off the avenue to accepting God’s salvation. Jesus referred to it as the unforgivable sin. Forgiveness must be accepted. Not accepting it leaves one ... surprise .. unforgiven.